The study of the outer shelf and the continental slope waters of the Eurasian Arctic seas has revealed a general trend in the surface pCO2 distribution, which manifested as an increase in pCO2 values eastward. It has been shown that the influence of terrestrial discharge on the carbonate system of East Siberian Arctic sea surface waters is not limited to the shallow shelf and that contemporary climate change impacts the carbon cycle of the Eurasian Arctic Ocean and influences air–sea CO2 flux.
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Continuous, highly abundant and well-preserved fossil ostracodes were studied from radiocarbon-dated sediment cores collected on the Lomonosov Ridge (Arctic Ocean) that indicate varying oceanographic conditions during the last ~50 kyr. Ostracode assemblages from cores taken during the SWERUS-C3 2014 Expedition, Leg 2, reflect paleoenvironmental changes during glacial, deglacial, and interglacial transitions, including changes in sea-ice cover and Atlantic Water inflow into the Eurasian Basin.
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This study tests the hypothesis that SGD exists in the Siberian Arctic shelf seas, but its dynamics may be largely controlled by complicated geocryological conditions such as permafrost. The permafrost cements rocks, forms a confining bed, and as a result makes it difficult for the groundwater escape to the shelf surface. However, the discovery of subterranean outcrops of groundwater springs in the Buor-Khaya Gulf are clear evidence that a groundwater flow system exists in the environment.
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Past glacial activity on the East Siberian continental margin is poorly known, partly due to the lack of geomorphological evidence. Here we present geophysical mapping and sediment coring data from the East Siberian shelf and slope revealing the presence of a glacially excavated cross-shelf trough reaching to the continental shelf edge north of the De Long Islands. The data provide direct evidence for extensive glacial activity on the Siberian shelf that predates the Last Glacial Maximum.
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In this study we investigate land-to-ocean transfer and the fate of permafrost carbon in the East Siberian Sea from the early Holocene until the present day. Our results suggest that there was a high input of terrestrial organic carbon to the East Siberian Sea during the last glacial–interglacial period caused by permafrost destabilisation. This material was mainly characterised as relict Pleistocene permafrost deposited via coastal erosion as a result of the sea level rise.
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Recent Arctic studies suggest that sea-ice decline and permafrost thawing will affect the phytoplankton in the Arctic Ocean. However, in what way the plankton composition will change as the warming proceeds remains elusive. Here we show that the carbon composition of plankton might change as a function of the enhanced terrestrial organic carbon supply and progressive sea-ice thawing.
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Based on mineral records from the northern Chukchi Sea, we report a long-term decline in the Beaufort Gyre (BG) strength during the Holocene, consistent with a decrease in summer insolation. Multi-centennial variability in BG circulation is consistent with fluctuations in solar irradiance. The Bering Strait inflow shows intensification during the middle Holocene, associated with sea-ice retreat and an increase in marine production in the Chukchi Sea, which is attributed to a weaker Aleutian Low.
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Global sea level rise during the last deglacial flooded the Siberian continental shelf in the Arctic Ocean. Sediment cores, radiocarbon dating, and microfossils show that the regional sea level in the Arctic rose rapidly from about 12 500 to 10 700 years ago. Regional sea level history on the Siberian shelf differs from the global deglacial sea level rise perhaps due to regional vertical adjustment resulting from the growth and decay of ice sheets.
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The Arctic and Pacific oceans are connected by the presently ~53 m deep Bering Strait. During the last glacial period when the sea level was lower than today, the Bering Strait was exposed. Humans and animals could then migrate between Asia and North America across the formed land bridge. From analyses of sediment cores and geophysical mapping data from Herald Canyon north of the Bering Strait, we show that the land bridge was flooded about 11 000 years ago.
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Recent data suggest that a 1 km thick ice shelf extended over the glacial Arctic Ocean during MIS 6, about 140 000 years ago. Here, we theoretically analyse the development and equilibrium features of such an ice shelf. The ice shelf was effectively dammed by the Fram Strait and the mean ice-shelf thickness was controlled primarily by the horizontally integrated mass balance. Our results can aid in resolving some outstanding questions of the state of the glacial Arctic Ocean.
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Continental slopes north of the East Siberian Sea are assumed to hold large amounts of methane. We present pore water chemistry from the 2014 SWERUS-C3 expedition. These are among the first results generated from this vast climatically sensitive region, and they imply that abundant methane, including gas hydrates, do not characterize the East Siberian Sea slope or rise. This contradicts previous modeling and discussions, which due to the lack of data are almost entirely based assumption.
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Vast Arctic methane deposits may alter global climate and require remote sensing (RS) to map. Sonar has great promise, but quantitative inversion based on theory is challenged by multiple bubble acoustical scattering in plumes. We demonstrate use of a real-world in situ bubble plume calibration using a bubble model to correct for differences in the calibration and seep plumes. Spatial seep sonar maps were then used to improve understanding of subsurface geologic controls.
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In this manuscript, we present the results of our study conducted for a sediment core (ARC4-BN05) collected in the Arctic Ocean. Detailed examination of clay and bulk mineralogy along with grain size, content of Ca and Mn, and planktonic foraminiferal numbers in core ARC4–BN05 provides important new information about sedimentary environments and provenance. Based on these proxies, we try to reveal late to middle Pleistocene glacial history.
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The Arctic Ocean, especially the Siberian shelves, overlays large areas of subsea permafrost that is degrading. We show that methane with a biogenic origin is emitted from this permafrost. At locations where bubble plumes have been observed, methane can escape oxidation in the surface sediment and rapidly migrate through the very shallow water column of this region to escape to the atmosphere, generating a positive radiative feedback.
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We use data collected in 2014 to show that the outflow of nutrient-rich water occurs much further to the west than has been reported in the past. We suggest that this is due to much less summer sea-ice coverage in the northwestern East Siberian Sea than in the past decades. Further, our data support a more complicated flow pattern in the region where the Mendeleev Ridge reaches the shelf compared to the general cyclonic circulation within the individual basins as suggested historically.
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The potential oxidation of land-derived organic material material in shelf sediments of the Arctic Ocean can have a large influence for the Arctic marine carbon budget. We studied the active degradation of land- and marine-derived organic material in East Siberian shelf sediment and found that the total amount of carbon dioxide produced was about 16 × 1012 g C/year. Terrestrial organic material contributed 0.3 to 0.5 × 1012 g C/year and plays a minor role in the outer Siberian shelf carbon budget.
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The eruption of the Alaskan Aniakchak volcano of 3.6 thousand years ago was one of the largest Holocene eruptions worldwide. The resulting ash is found in several Alaskan sites and as far as Newfoundland and Greenland. In this study, we found ash from the Aniakchak eruption in a marine sediment core from the western Chukchi Sea in the Arctic Ocean. Combined with radiocarbon dates on mollusks, the volcanic age marker is used to calculate the marine radiocarbon reservoir age at that time.
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Waters with very high p>CO2, nutrients and low oxygen concentrations were observed along the continental margin of the East Siberian Sea and well out into the deep Makarov and Canada basins during the SWERUS-C3 expedition in 2014. This water had a low saturation state with respect to calcium carbonate, down to less than 0.8 for calcite and 0.5 for aragonite, and is traced in historic data to the Canada Basin and in the waters flowing out of the Arctic Ocean in the western Fram Strait.
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In this study we quantify key carbon cycling processes on the East Siberian Arctic Shelf. A specific aim is to determine the pathways of terrestrial organic carbon (OC) supplied by rivers and coastline erosion – and particularly to what extent degradation of terrestrial OC contributes to air-sea CO2 exchange. We estimate that the shelf is a weak CO2 sink, although this sink is considerably reduced mainly by degradation of eroded OC and to a lesser extent by degradation of riverine OC.
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We investigate late Pleistocene permafrost at the Buor Khaya Peninsula (Laptev Sea, Siberia) for cryolithological, geochemical, and geochronological parameters. The sequences were composed of ice-oversaturated silts and fine-grained sands with 0.2 to 24 wt% of organic matter. The deposition was between 54.1 and 9.7 kyr BP. Due to coastal erosion, the biogeochemical signature of the deposits represents the terrestrial end-member, and is related to organic matter deposited in the marine realm.
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Organic matter stored in permafrost will start decomposing due to climate warming. To better understand its composition in ice-rich Yedoma, we analyzed ancient sedimentary DNA, pollen and non-pollen palynomorphs throughout an 18.9 m long permafrost core. The combination of both proxies allow an interpretation both of regional floristic changes and of the local environmental conditions at the time of deposition.
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The analysis of microbial lipid (GDGTs) in three sediment cores from the northern Chukchi Sea margin provides insights into GDGTs production, sources and SST in this region of the Arctic during the Holocene. Different patterns in GDGTs distribution between cores may indicate spatial differences in the pathways of Pacific waters and sea-ice extent. TEX86 and TEX86L indices potentially useful for SST reconstruction show millennial-scale variability, but the controls are not well understood.
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Fluvial discharge and coastal erosion of the permafrost-dominated East Siberian Arctic delivers large quantities of terrigenous organic carbon (Terr-OC) to marine waters. We assessed its fate and composition in different marine pools with a suite of biomarkers. The dissolved organic carbon is transporting off-shelf “young” and fresh vascular plant material, while sedimentary and near-bottom particulate organic carbon preferentially carries old organic carbon released from thawing permafrost.
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Manuscript not accepted for further review(discussion: closed, 4 comments)

Short summary

We report mineral records in two sediment cores from the northern Chukchi Sea providing insights into the long-term dynamics of the Arctic currents during the Holocene. We found a long-term decline in the BG strength, consistent with decrease in summer insolation. The millennial to multi-centennial variability is consistent with fluctuations in solar irradiance. The BSI shows intensification during the middle Holocene, which is attributed to a weak Aleutian Low.
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The permafrost in eastern Siberia contains large amounts of carbon frozen in soils and sediments. Continuing global warming is thawing the permafrost and releasing carbon to the Arctic Ocean. We used pyrolysis-GCMS, a chemical fingerprinting technique, to study the types of carbon being deposited on the continental shelf. We found large amounts of permafrost-sourced carbon being deposited up to 200 km offshore.
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Thawing permafrost may release large amounts of terrestrial organic carbon (TerrOC) to the Arctic Ocean. We assessed its fate in the marine environment with a suite of biomarkers. Across the Laptev Sea their concentrations in surface sediments decreased significantly and showed a trend to qualitatively more degraded TerrOC with increasing water depth. We infer that the degree of degradation of TerrOC is a function of the time spent under oxic conditions during protracted cross-shelf transport.
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The Arctic contains a large pool of carbon that is vulnerable to warming and can be released by rivers and coastal erosion. We study microbial lipids (BHPs) in permafrost and shelf sediments to trace the source, transport and fate of this carbon. BHPs in permafrost deposits are released to the shelf by rivers and coastal erosion, in contrast to other microbial lipids (GDGTs) that are transported by rivers. Several further analyses are needed to understand the complex East Siberian Shelf system.
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